Good at
Bid adjustment at a scale and frequency no human matches, given enough conversion data. Finding query variations. Allocating within defined constraints.
Bad at
Knowing your margin. Knowing your stock. Knowing that last week’s spike was a PR mention. Knowing that a product is about to be discontinued.
Cannot do at all
Decide what is worth selling, judge whether the offer is competitive, or tell you the maths does not work.
What that implies
The job moved from adjusting bids to defining constraints and feeding good data. That is less glamorous and considerably more consequential.